#region License

/*
 * Copyright ?2002-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#endregion

#region Imports

using System;
using System.ComponentModel;
using System.Configuration;
using System.Globalization;
using System.Xml;

#endregion

namespace Spring.Core.TypeConversion
{
    /// <summary>
    /// Custom <see cref="System.ComponentModel.TypeConverter"/> implementation for
    /// <see cref="System.Collections.Specialized.NameValueCollection"/> objects.
    /// </summary>
    /// <remarks>
    /// <p>
    /// Handles conversion from an <b>XML formatted string</b> to a
    /// <see cref="System.Collections.Specialized.NameValueCollection"/> object
    /// (see below for an example of the expected XML format).
    /// </p>
    /// <p>
    /// This converter must be registered before it will be available. Standard
    /// converters in this namespace are automatically registered by the
    /// <see cref="Spring.Objects.ObjectWrapper"/> class.
    /// </p>
    /// </remarks>
    /// <example>
    /// <p>
    /// Find below some examples of the XML formatted strings that this
    /// converter will sucessfully convert. Note that the name of the top level
    /// (document) element is quite arbitrary... it is only the content that
    /// matters (and which must be in the format
    /// <c>&lt;add key="..." value="..."/&gt;</c>. For your continued sanity
    /// though, you may wish to standardize on the top level name of
    /// <c>'dictionary'</c> (although you are of course free to not do so).
    /// </p>
    /// <code escaped="true">
    /// <dictionary>
    ///		<add key="host" value="localhost"/>
    ///		<add key="port" value="8080"/>
    /// </dictionary>
    /// </code>
    /// <p>
    /// The following example uses a different top level (document) element
    /// name, but is equivalent to the first example.
    /// </p>
    /// <code escaped="true">
    /// <web-configuration-parameters>
    ///		<add key="host" value="localhost"/>
    ///		<add key="port" value="8080"/>
    /// </web-configuration-parameters>
    /// </code>
    /// </example>
    /// <author>Rod Johnson</author>
    /// <author>Juergen Hoeller</author>
    /// <author>Simon White (.NET)</author>
    internal class NameValueConverter : TypeConverter
    {
        #region Constructor (s) / Destructor

        /// <summary>
        /// Creates a new instance of the
        /// <see cref="Spring.Core.TypeConversion.NameValueConverter"/> class.
        /// </summary>
        public NameValueConverter()
        {
        }

        #endregion

        /// <summary>
        /// Returns whether this converter can convert an object of one
        /// <see cref="System.Type"/> to a
        /// <see cref="System.Collections.Specialized.NameValueCollection"/>
        /// </summary>
        /// <remarks>
        /// <p>
        /// Currently only supports conversion from an
        /// <b>XML formatted</b> <see cref="System.String"/> instance.
        /// </p>
        /// </remarks>
        /// <param name="context">
        /// A <see cref="System.ComponentModel.ITypeDescriptorContext"/>
        /// that provides a format context.
        /// </param>
        /// <param name="sourceType">
        /// A <see cref="System.Type"/> that represents the
        /// <see cref="System.Type"/> you want to convert from.
        /// </param>
        /// <returns>True if the conversion is possible.</returns>
        public override bool CanConvertFrom(
            ITypeDescriptorContext context,
            Type sourceType)
        {
            if (sourceType == typeof(string))
            {
                return true;
            }
            return base.CanConvertFrom(context, sourceType);
        }

        /// <summary>
        /// Convert from a string value to a
        /// <see cref="System.Collections.Specialized.NameValueCollection"/> instance.
        /// </summary>
        /// <param name="context">
        /// A <see cref="System.ComponentModel.ITypeDescriptorContext"/>
        /// that provides a format context.
        /// </param>
        /// <param name="culture">
        /// The <see cref="System.Globalization.CultureInfo"/> to use
        /// as the current culture. 
        /// </param>
        /// <param name="value">
        /// The value that is to be converted.
        /// </param>
        /// <returns>
        /// A <see cref="System.Collections.Specialized.NameValueCollection"/>
        /// if successful. 
        /// </returns>
        public override object ConvertFrom(
            ITypeDescriptorContext context,
            CultureInfo culture, object value)
        {
            string text = value as string;
            if (text != null)
            {
                XmlDocument doc = new XmlDocument();
                doc.LoadXml(text);
                return new NameValueSectionHandler()
                    .Create(null, null, doc.DocumentElement);
            }
            return base.ConvertFrom(context, culture, value);
        }
    }
}